The risk for depression is nearly twice as great among nursing home residents as it is for community-residing elders, with up to 50 percent of nursing home residents affected by significant depressive symptoms. Although we now have a good understanding of the epidemiology and manifestations of depression in late life, and are beginning to apply effective treatments to some groups of elders, the benefits of the past decade of research have yet to reach the frailest elders living in nursing homes. Depression in long-term care is a significant public health issue. The health and cognitive multiple comorbidity of this population makes treatment, and treatment research, extremely challenging. The broad goal of this proposal is to adapt an efficacious psychosocial intervention for depression to the nursing home setting, using the public health model of intervention research and the exploratory/development mechanism provided by NIMH for implementing such work. There are 3 specific aims: (1) To use a collaborative treatment development process involving nursing home staff to adapt a behavioral intervention for treating depression in elders with cognitive impairment to nursing home residents with a range of physical and cognitive abilities; (2) to conduct a pilot effectiveness study on the adapted intervention, using a replicated, single-subject design, in 2-3 nursing homes other than the one in which the initial treatment development process took place, and (3) as a part of the effectiveness study, to collect data on staff outcomes and cost effectiveness. The treatment has a behavioral theoretical basis, and focuses on increasing opportunity for pleasant events to increase levels of activity and positive affect. Treatment is implemented primarily by existing nursing facility staff, with supervision from a licensed psychologist, making ultimate dissemination of this treatment practical and affordable. Standardizing the treatment collaboratively with staff insures a high level of staff acceptance and maximizes feasibility in the nursing home setting. The treatment evaluation design employs a replicated, multiple-baselines-within-subjects design and Hierarchical Linear Modeling, optimizing features from single-case and group research. Each participant will be observed for a minimum of a two-week baseline, followed by six weeks of active intervention, four weeks of maintenance, and a three-month follow-up. Measures include comprehensive psychiatric evaluation and diagnosis, depression and mood rating scales, observed affect and activity participation, behavior problems, and staff burden. The end-product of the work will be a standardized treatment protocol ready for formal multi-site intervention trials.